Biometric, nutritional and sensory characteristic modifications in farmed Murray cod ( Maccullochella peelii peelii) during the purging process

Intensively farmed, market-size Murray cod (~ 600 g), were purged (transferred into a clean water system and starved) and sampled at three day intervals for a total of 18 days (D0, D3, D6, D9, D12, D15 and D18). Purged fish lost from 6% (D3) to 14% (D18) body weight, and the weight loss was highly correlated to the number of days of purging/starvation. Condition factor and Hepatosomatic Index decreased significantly ( P < 0.05) only after 18 days of purging compared to the control (D0). Fillet lipid content (%) did not vary during the trial. Eicosapentaenoic acid (EPA: 20:5 n−3) decreased and docosapentaenoic acid (DPA: 22:5 n−3) increased ( P < 0.05) during the trial, while docosahexaenoic acid (DHA: 22:6 n−3) did not show any significant variation. Purging contributed positively to the improvement of the volatile flavour compound composition, with a significant ( P < 0.05) reduction in total volatile aldehydes and an increase in total volatile hydrocarbons. Since no major differences were found between samples during the last stages of the purging process (D12, D15 and D 18), it is possible to conclude that, under these experimental conditions, 12 days is the minimum duration to obtain an improvement in the volatile compound profile of intensively farmed Murray cod whilst keeping body weight loss to a minimum.